Laravel 5.4 migration: Specified key was too long error solution

Three days ago Laravel 5.4 was released, so I have decided to give it a try. I have made a new Laravel 5.4 project and just when I was about to run the default auth migrations that are shipped with the Laravel almost without any other changes, I got these two red errors:

What the hell is going on!?!? I have checked the migrations file and everything was okay there unchanged compared to Laravel 5.3. But, according to Laravel Documentation one thing changed:

Laravel 5.4 uses the utf8mb4 character set by default, which includes support for storing “emojis” in the database. If you are upgrading your application from Laravel 5.3, you are not required to switch to this character set.

And, according to their documentation the problem is that I’m running version of MySQL prior to 5.7.7 or MariaDB prior to 10.2.2 (my case). In case you are running versions of MySQL or MariaDB greater than these than most probably that you won’t have this problem at all.

In case you are having this problem – here are the possible solutions:

1. Upgrade MariaDB / MySQL

To update MariaDB on Mac using Brew, first you need to unlink the current one using:

brew unlink mariadb

and then install a dev one using

brew install mariadb --devel

That will install MariaDB version 10.2.3 that works fine. Remember that after installation is done you need to stop/start the service:

brew services stop mariadb
brew services start mariadb

2. Stick with utf8

In case you don’t want to use the utf8mb4 (that is now setup by default in Laravel 5.4) – instead you want to stick with utf8 that was in use in Laravel 5.3 and all versions before, simply edit/config/database.php and find these two lines in mysql driver:

'charset' => 'utf8mb4',
'collation' => 'utf8mb4_unicode_ci',

and replace them with with

'charset' => 'utf8',
'collation' => 'utf8_unicode_ci',

That will stop using the utf8mb4 and will change back to utf8. The good thing about this is that you’ll be able to fit 25% more characters into the same columns in database compared with utf8mb4 and that you’ll be able to use existing databases and projects without the need of converting them if you don’t want to. And the downside is that some characters will not be able to be saved to database like this mac command character ⌘ or some emojis. Utf8 can only store Plane Unicode while utf8mb4 can store any unicode character. Utf8mb4 is also 100% backwards compatible with utf8.

3. Use utf8mb4 without MySQL/MariaDB upgrade

In case you want to use utf8mb4 but you don’t want to or simply can’t upgrade your MySQL/MariaDB there is a simple solution proposed by Laravel documentation. All you need to do is edit AppServiceProvider located at App\Providers\AppServiceProvider.php and add the following line to the boot() method and load the Schema facade:

What that will do is actually change the default maximum field length in the database and actually shorten your maximum string length from 255 to maximum of 191 characters (utf8 uses 3 bytes per character while utf8mb4 uses 4 bytes per character your field can now hold 25% less characters 255 * 75% = 191.25). So if you don’t set the string field by hand in the migration the new default will be 191. You can increase the length if you need it manually by defining it:

$table->string('name', 255);

But this will not be possible on indexed fields since these can’t be longer than 191 characters. So keep this in mind in case you’re planing to use utf8mb4.

In case you want to convert the database from utf8 to utf8mb4 for any existing projects or if you are upgrading from Larvel 5.3 or older to Laravel 5.3 this is the code you need to run for every database, table and column:

Make sure you have the database backups before making these changes!!!!

# For each database:
ALTER DATABASE database_name CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;
# For each table:
ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
# For each column:
ALTER TABLE table_name CHANGE column_name column_name VARCHAR(191) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
# (Don’t just blindly copy-paste this! The exact statement depends on the column type, maximum length, and other properties. The above line is just an example for a `VARCHAR` column.)

Once again: when converting from utf8 to utf8mb4, the maximum length of a column or index key is unchanged in terms of bytes but since utf8mb4 uses 25% more bytes per character your columns can now accept less characters. Therefore, it is smaller in terms of characters, because the maximum length of a character is now four bytes instead of three.

For example, a TINYTEXT column can hold up to 255 bytes, which correlates to 85 three-byte or 63 four-byte characters. Let’s say you have a TINYTEXT column that uses utf8 but must be able to contain more than 63 characters. Given this requirement, you can’t convert this column to utf8mb4 unless you also change the data type to a longer type such as TEXT — because if you’d try to fill it with four-byte characters, you’d only be able to enter 63 characters, but not more.

The same goes for index keys. The InnoDB storage engine has a maximum index length of 767 bytes, so for utf8 or utf8mb4 columns, you can index a maximum of 255 or 191 characters, respectively. If you currently have utf8 columns with indexes longer than 191 characters, you will need to index a smaller number of characters when using utf8mb4.

If you plan on using utf8mb4 make sure to setup your MySQL server accordingly by editing /etc/my.cnf file accordingly:

Conclusion

If your application won’t use any special characters or emojis or languages such as Chinese, Japanese, and Korean you’re most probably fine sticking with utf8. But if you can – you should move to utf7mb4 since that will stop you from loosing 4-byte characters when a user ads these in comments or in message or whenever you store these in your database. You should always strive to full unicode support everywhere in your apps and updating your database and code might take some time but it’s definitely worth the time and effort.

You’ll need to install DEV version of MariaDB using: “brew install mariadb –devel” then just restart it and that should work… I had to do that myself too to get the latest MariaDB (that supports this).

I really can’t comment on that since I’m using MariaDB for development on my Mac but would like to know more about your problem. What error message do you get? Have you tried upgrading? What of the 3 solutions have you tried etc.